Journal articles: 'Standard solar models'

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Bahcall, John N. "Standard solar models." Nuclear Physics B - Proceedings Supplements 77, no. 1-3 (May 1999): 64–72. http://dx.doi.org/10.1016/s0920-5632(99)00399-0.

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Ciacio, F., S. Degl'Innocenti, and B. Ricci. "Updating standard solar models." Astronomy and Astrophysics Supplement Series 123, no. 3 (June 1997): 449–54. http://dx.doi.org/10.1051/aas:1997168.

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Castellani, V., S. Degl'Innocenti, G. Fiorentini, M. Lissia, and B. Ricci. "Solar neutrinos: beyond standard solar models." Physics Reports 281, no. 5-6 (March 1997): 309–98. http://dx.doi.org/10.1016/s0370-1573(96)00032-4.

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Degl'Innoccenti, S., W. A. Dziembowski, G. Fiorentini, and B. Ricci. "Helioseismology and standard solar models." Astroparticle Physics 7, no. 1-2 (June 1997): 77–95. http://dx.doi.org/10.1016/s0927-6505(97)00004-2.

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Vinyoles, N., A. Serenelli, and F. L. Villante. "The B16 Standard Solar Models." Journal of Physics: Conference Series 1056 (July 2018): 012058. http://dx.doi.org/10.1088/1742-6596/1056/1/012058.

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Bahcall, John N., M. H. Pinsonneault, Sarbani Basu, and J. Christensen-Dalsgaard. "Are Standard Solar Models Reliable?" Physical Review Letters 78, no. 2 (January 13, 1997): 171–74. http://dx.doi.org/10.1103/physrevlett.78.171.

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Serenelli, Aldo M. "New results on standard solar models." Astrophysics and Space Science 328, no. 1-2 (November 3, 2009): 13–21. http://dx.doi.org/10.1007/s10509-009-0174-8.

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Bahcall, John N. "Recent work on standard solar models." Nuclear Physics B - Proceedings Supplements 31 (April 1993): 125–28. http://dx.doi.org/10.1016/0920-5632(93)90123-n.

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Maeder, André. "A Look on Non-Standard Solar Models." International Astronomical Union Colloquium 121 (1990): 133–44. http://dx.doi.org/10.1017/s0252921100067889.

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AbstractA short review of some of the non–standard models proposed in these last two decades is presented. Their main physical assumptions are shown, as well as the way they meet or do not meet the various observational constraints.

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Vinyoles, Núria, Aldo M. Serenelli, Francesco L. Villante, Sarbani Basu, Johannes Bergström, M. C. Gonzalez-Garcia, Michele Maltoni, Carlos Peña-Garay, and Ningqiang Song. "A New Generation of Standard Solar Models." Astrophysical Journal 835, no. 2 (January 31, 2017): 202. http://dx.doi.org/10.3847/1538-4357/835/2/202.

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Elsworth, Y., R. Howe, G. R. Isaak, C. P. McLeod, and R. New. "Evidence from solar seismology against non-standard solar-core models." Nature 347, no. 6293 (October 1990): 536–39. http://dx.doi.org/10.1038/347536a0.

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Bahcall, J. N., and M. Cribier. "The Standard Solar Model." International Astronomical Union Colloquium 121 (1990): 21–41. http://dx.doi.org/10.1017/s0252921100067798.

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AbstractThe main features of standard solar models, the logic of the calculations, and some of the important results concerning solar neutrinos experiments are given. The input parameters that cause the greatest uncertainties in the calculated neutrino fluxes are the nuclear rection rates, the chemical abundances, the radiative opacity, and the equation of state. This article is based, with permission of the publisher, on Chapters 1 and 4 of Neutrino Astrophysics by J. N. Bahcall, Cambridge University Press (1989).

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Bahcall, John N., Aldo M. Serenelli, and Sarbani Basu. "10,000 Standard Solar Models: A Monte Carlo Simulation." Astrophysical Journal Supplement Series 165, no. 1 (July 2006): 400–431. http://dx.doi.org/10.1086/504043.

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Guzik, Joyce A., L. A. Willson, and Wendee M. Brunish. "A comparison between mass-losing and standard solar models." Astrophysical Journal 319 (August 1987): 957. http://dx.doi.org/10.1086/165512.

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Robinson, S. J. "On Solar Neutrinos and Chemically Inhomogeneous Solar Models." Publications of the Astronomical Society of Australia 7, no. 2 (1987): 139–40. http://dx.doi.org/10.1017/s1323358000022098.

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AbstractWork is in progress on the extension of a detailed stellar structure code to explore a suggested solution to the Solar Neutrino Problem where the Sun has a small (∼0.01M⊙) high-Z core on entry to the ZAMS. A basic premise of such models is that the core will burn itself out by solar age and the model acquire a neutrino luminosity in line with that observed. The work to date has involved the construction of a standard solar model and, currently, the development of inhomogeneous models with associated adjustments to the structure equations.

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Bahcall, J. N., and M. H. Pinsonneault. "Standard solar models, with and without helium diffusion, and the solar neutrino problem." Reviews of Modern Physics 64, no. 4 (October 1, 1992): 885–926. http://dx.doi.org/10.1103/revmodphys.64.885.

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Berezinsky, V., G. Fiorentini, and M. Lissia. "The MSW solution to the solar neutrino problem for non-standard solar models." Physics Letters B 341, no. 1 (December 1994): 38–45. http://dx.doi.org/10.1016/0370-2693(94)01204-0.

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Salmon, S. J. A. J., G. Buldgen, A. Noels, P. Eggenberger, R. Scuflaire, and G. Meynet. "Standard solar models: Perspectives from updated solar neutrino fluxes and gravity-mode period spacing." Astronomy & Astrophysics 651 (July 2021): A106. http://dx.doi.org/10.1051/0004-6361/202140769.

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Context. Thanks to the vast and exquisite set of observations that have been made available for the Sun, our star is by far an ideal target for testing stellar models with a unique precision. A recent issue under consideration in the field is related to the progress in the solar surface abundances derivation that has led to a decrease of the solar metallicity. While the former high-metallicity models were in fair agreement with other observational indicators from helioseismology and solar neutrino fluxes, it is no longer the case for low-metallicity models. This issue has become known as ‘the solar problem’. Recent data are, however, promising to shed a new light on it. For instance, in 2020, the Borexino Collaboration released the first-ever complete estimate of neutrinos emitted in the CNO cycle, which has reaffirmed the role of the neutrino constraints in the solar modelling process and their potential in exploring related issues. In parallel, a newly claimed detection of solar gravity modes of oscillation offers another opportunity for probing the stratification in the Sun’s central layers. Aims. We propose combining the diagnoses from neutrinos and helioseismology, both from pressure and gravity modes, in assessing the predictions of solar models. We compare in detail the different physical prescriptions currently at our disposal with regard to stellar model computations. Methods. We build a series of solar standard models based on a variation of the different physical ingredients directly affecting the core structure: opacity, chemical mixture, nuclear reactions rates. We compare the predictions of these models to their observational counterparts for the neutrinos fluxes, gravity-mode period spacing, and low-degree pressure mode frequency ratios. Results. The CNO neutrino flux confirms previous findings, exhibiting a preference for high-metallicity models. Nevertheless, we find that mild modification of the nuclear screening factors can re-match low-metallicity model predictions to observed fluxes, although it does not restore the agreement with the helioseismic frequency ratios. Neither the high-metallicity or low-metallicity models are able to reproduce the gravity-mode period spacing. The disagreement is huge, more than 100σ to the observed value. Reversely, the family of standard models narrows the expected range of the Sun’s period spacing: between ∼2150 and ∼2190 s. Moreover, we show this indicator can constrain the chemical mixture, opacity, and – to a lower extent – nuclear reactions in solar models.

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BAHCALL, JOHN N. "SOLAR MODELS: AN HISTORICAL OVERVIEW." International Journal of Modern Physics A 18, no. 22 (September 10, 2003): 3761–76. http://dx.doi.org/10.1142/s0217751x03017166.

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I will summarize in four slides the 40 years of development of the standard solar model that is used to predict solar neutrino fluxes and then describe the current uncertainties in the predictions. I will dispel the misconception that the p-p neutrino flux is determined by the solar luminosity and present a related formula that gives, in terms of the p-p and 7 Be neutrino fluxes, the ratio of the rates of the two primary ways of terminating the p-p fusion chain. I will also attempt to explain why it took so long, about three and a half decades, to reach a consensus view that new physics is being learned from solar neutrino experiments. Finally, I close with a personal confession and some personal remarks.

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Buldgen, G., P. Eggenberger, V. A. Baturin, T. Corbard, J. Christensen-Dalsgaard, S. J. A. J. Salmon, A. Noels, A. V. Oreshina, and R. Scuflaire. "Seismic solar models from Ledoux discriminant inversions." Astronomy & Astrophysics 642 (October 2020): A36. http://dx.doi.org/10.1051/0004-6361/202037980.

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Context. The Sun constitutes an excellent laboratory of fundamental physics. With the advent of helioseismology, we were able to probe its internal layers with unprecendented precision and thoroughness. However, the current state of solar modelling is still stained by tedious issues. One of these central problems is related to the disagreement between models computed with recent photospheric abundances and helioseismic constraints. The observed discrepancies raise questions on some fundamental ingredients entering the computation of solar and stellar evolution models. Aims. We used solar evolutionary models as initial conditions for reintegrating their structure using Ledoux discriminant inversions. The resulting models are defined as seismic solar models, satisfying the equations of hydrostatic equilibrium. These seismic models will allow us to better constrain the internal structure of the Sun and provide complementary information to that of calibrated standard and non-standard models. Methods. We used inversions of the Ledoux discriminant to reintegrate seismic solar models satisfying the equations of hydrostatic equilibrium. These seismic models were computed using various reference models with different equations of state, abundances, and opacity tables. We checked the robustness of our approach by confirming the good agreement of our seismic models in terms of sound speed, density, and entropy proxy inversions, as well as frequency-separation ratios of low-degree pressure modes. Results. Our method allows us to determine the Ledoux discriminant profile of the Sun with an excellent accuracy and compute full profiles of this quantity. Our seismic models show an agreement with seismic data of ≈0.1% in sound speed, density, and entropy proxy after seven iterations in addition to an excellent agreement with the observed frequency-separation ratios. They surpass all standard and non-standard evolutionary models including ad hoc modifications of their physical ingredients that aim to reproduce helioseismic constraints. Conclusions. The obtained seismic Ledoux discriminant profile, as well as the full consistent structure obtained from our reconstruction procedure paves the way for renewed attempts at constraining the solar modelling problem and the missing physical processes acting in the solar interior by breaking free from the hypotheses of evolutionary models.

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Degl’Innocenti, Scilla. "Stellar evolution and the Standard Solar Model." EPJ Web of Conferences 227 (2020): 01004. http://dx.doi.org/10.1051/epjconf/202022701004.

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This contribution is meant as a very brief introduction to the principal concepts of stellar physics. First the main physical processes active in stellar structures will be shortly described, then the most important features during the stellar life-cycle up to the central H exhaustion will be summarized with partic-ular attention to the description of solar models.

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Brun, A. S., S. Turck‐Chieze, and P. Morel. "Standard Solar Models in the Light of New Helioseismic Constraints. I. The Solar Core." Astrophysical Journal 506, no. 2 (October 20, 1998): 913–25. http://dx.doi.org/10.1086/306271.

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MORRISON, DOUGLAS R. O. "UPDATED REVIEW OF SOLAR MODELS AND SOLAR NEUTRINO EXPERIMENTS." International Journal of Modern Physics D 01, no. 02 (January 1992): 281–302. http://dx.doi.org/10.1142/s0218271892000148.

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The Conventional Wisdom that there is a Solar Neutrino Problem and that New Physics is required, is examined. The various solar evolutionary models, (or SSM), are described and in particular the four new 1992 papers. While the evolutionary models are generally robust, there are important assumptions and uncertainties (screening, nuclear reaction rates, etc.) which mean that the errors cannot be small. Diffusion in the Sun is expected to be significant but so far there is no calculation which includes all types of diffusion, especially turbulent diffusion. The new and important helioseismological results are shown to to be in agreement with some of the SSM calculations. The experimental results are beginning to be not inconsistent with the SSM calculations. Kamiokande is consistent with SSM calculations except for one with rather small errors. The new GALLEX result is in agreement with all SSM calculations within 1.3 to 2 standard deviations. The 1990 SAGE I experiment is shown to have no evidence of solar neutrinos and is inconsistent with all SSM calculations and with GALLEX. However the new 1991 SAGE II experiment finds neutrino rates not inconsistent with SSM calculations. The Chlorine experiment is significantly below SSM calculations and is inconsistent with Kamiokande. In particular the Chlorine claim that there is a variation of the solar neutrino flux with the inverse of the sunspot activity, which shows a correlation of five standard deviation significance, is in contradiction with the results of the Kamiokande experiment which finds no variation of the solar neutrino flux with time. The overall conclusion is that there is no compelling evidence for a Solar Neutrino Problem or need for New Physics. However the neutrinos could still have masses and further experiments with higher statistics are essential as they are one of the rare ways of studying this low mass region. Thus the Solar Neutrino Problem is becoming a Neutrino Mass Quest.

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Zhou, Tianhong. "Expected sensitivity to test of standard solar models with future solar CNO neutrino flux measurement." Journal of Physics: Conference Series 2012, no. 1 (September 1, 2021): 012114. http://dx.doi.org/10.1088/1742-6596/2012/1/012114.

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Picariello, Marco, João Pulido, S. Andringa, N. F. Barros, and J. Maneira. "SNO+: predictions from standard solar models and resonant spin flavour precession." Journal of High Energy Physics 2007, no. 11 (November 20, 2007): 055. http://dx.doi.org/10.1088/1126-6708/2007/11/055.

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Myhre, G., and B. H. Samset. "Standard climate models radiation codes underestimate black carbon radiative forcing." Atmospheric Chemistry and Physics Discussions 14, no. 19 (October 20, 2014): 26173–86. http://dx.doi.org/10.5194/acpd-14-26173-2014.

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Abstract. Radiative forcing (RF) of black carbon (BC) in the atmosphere is estimated using radiative transfer codes of various complexities. Here we show that the 2-stream radiative transfer codes used most in climate models give too strong forward scattering, leading to enhanced absorption at the surface and too weak absorption by BC. Such calculations are found to underestimate RF by 10% for global mean, all sky conditions, relative to the more sophisticated multi-stream models. The underestimation occurs primarily for low surface albedo, even though BC is more efficient for absorption of solar radiation at high surface albedo.

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Ostlie, Dale A. "Nonlinear RR Lyrae Models and Double Mode Pulsation." International Astronomical Union Colloquium 111 (1989): 281. http://dx.doi.org/10.1017/s0252921100011891.

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AbstractNonlinear models of RR Lyrae variables were calculated in the region of the HR diagram containing double mode pulsation. In all models Teff = 7000 K, the luminosity was 60 times solar, X = 0.70, Y = 0.299, and P1/P0 = 0.746, characteristic of double mode RR Lyrae variables in M15 (Cox, Hodson, and Clancy, 1983). Models of 0.65 solar masses were calculated using standard opacities and models of 0.75 solar masses were calculated with opacities artificially enhanced by a factor of 1.2 between log(T) = 5.2 and log(T) = 5.9 (Andreasen and Petersen, 1988).

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Katiyar, A. K., and C. K. Pandey. "A Review of Solar Radiation Models—Part I." Journal of Renewable Energy 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/168048.

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Energy is considered as a key source for the future and plays a pivotal role in its socioeconomic development by raising the standard of living and the quality of life, not only for India but also for the world. In view of the scarce fossil fuel reserves, solar energy is one of the important sources of renewable energy used in India because of the suitable climate conditions. It receives about 5485.17 Wh/m2day of solar insolation with an annual total of about 19, 74, 661.2 Wh/m2. Except for the monsoon months, solar radiation incidence is very encouraging, from the application point of view. For the efficient functioning and better performance of solar energy device, the information of solar radiation and its components at particular location is very essential for designing the solar energy devices. Therefore, over the years, several empirical correlations have been developed in order to estimate the more appropriate solar radiation in India as well as around the world. Here we present a review of different solar radiation models which predict global solar radiation and discussed the long-term plan to meet future energy demand with renewable energy due to economy growth.

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Gelbwaser-Klimovsky, David, and Alán Aspuru-Guzik. "On thermodynamic inconsistencies in several photosynthetic and solar cell models and how to fix them." Chemical Science 8, no. 2 (2017): 1008–14. http://dx.doi.org/10.1039/c6sc04350j.

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Myhre, G., and B. H. Samset. "Standard climate models radiation codes underestimate black carbon radiative forcing." Atmospheric Chemistry and Physics 15, no. 5 (March 13, 2015): 2883–88. http://dx.doi.org/10.5194/acp-15-2883-2015.

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Abstract. Radiative forcing (RF) of black carbon (BC) in the atmosphere is estimated using radiative transfer codes of various complexities. Here we show that the two-stream radiative transfer codes used most in climate models give too strong forward scattering, leading to enhanced absorption at the surface and too weak absorption by BC in the atmosphere. Such calculations are found to underestimate the positive RF of BC by 10% for global mean, all sky conditions, relative to the more sophisticated multi-stream models. The underestimation occurs primarily for low surface albedo, even though BC is more efficient for absorption of solar radiation over high surface albedo.

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Castro, M., J. D. do Nascimento, J. S. da Costa, J. Meléndez, M. Bazot, S. Théado, G. F. Porto de Mello, and J. R. De Medeiros. "Lithium abundance as a boundary condition for age and mass determination of solar twin stars." Proceedings of the International Astronomical Union 5, S265 (August 2009): 422–23. http://dx.doi.org/10.1017/s1743921310001134.

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AbstractWe explore the non-standard mixing history of five solar twins to determine as precisely as possible their mass and age. For this, we computed a grid of evolutionary models with non-standard mixing at given metallicities with the Toulouse-Geneva code for a range of stellar masses. We choose the evolutionary model that best fit the low lithium abundances observed in the solar twins. Our best model for each solar twin provides a mass and age solution constrained by their Li content and Teff determination. Li depletion due to the additional mixing in solar-twins is strongly mass dependent. An accurate lithium abundance measurement connected with non-standard models provides a more precise information about the age and mass better than that determined only by classical methods.

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Ellis, A. N., and D. O. Gough. "Do solar models with weakly interacting massive particles reproduce the Stanford seismic data?" Symposium - International Astronomical Union 123 (1988): 111–14. http://dx.doi.org/10.1017/s0074180900157857.

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The discrepancy between theoretical eigenfrequencies of standard solar models and the frequencies of solar modes of degree between 2 and 5 measured at Stanford is degree-independent for cyclic frequencies above about 2 mHz. Below that frequency the discrepancy for dotriacontapole modes diverges from that of the modes of lower degree. The differences between eigenfrequencies of a simple solar model containing a cloud of weakly interacting particles in its core and of one without do not reproduce this behaviour.

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Chaturvedi, K., B. Willenborg, M. Sindram, and T. H. Kolbe. "SOLAR POTENTIAL ANALYSIS AND INTEGRATION OF THE TIME-DEPENDENT SIMULATION RESULTS FOR SEMANTIC 3D CITY MODELS USING DYNAMIZERS." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-4/W5 (October 23, 2017): 25–32. http://dx.doi.org/10.5194/isprs-annals-iv-4-w5-25-2017.

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Semantic 3D city models play an important role in solving complex real-world problems and are being adopted by many cities around the world. A wide range of application and simulation scenarios directly benefit from the adoption of international standards such as CityGML. However, most of the simulations involve properties, whose values vary with respect to time, and the current generation semantic 3D city models do not support time-dependent properties explicitly. In this paper, the details of solar potential simulations are provided operating on the CityGML standard, assessing and estimating solar energy production for the roofs and facades of the 3D building objects in different ways. Furthermore, the paper demonstrates how the time-dependent simulation results are better-represented inline within 3D city models utilizing the so-called Dynamizer concept. This concept not only allows representing the simulation results in standardized ways, but also delivers a method to enhance static city models by such dynamic property values making the city models truly dynamic. The dynamizer concept has been implemented as an Application Domain Extension of the CityGML standard within the OGC Future City Pilot Phase 1. The results are given in this paper.

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Myers, Daryl R., Keith Emery, and C. Gueymard. "Revising and Validating Spectral Irradiance Reference Standards for Photovoltaic Performance Evaluation." Journal of Solar Energy Engineering 126, no. 1 (February 1, 2004): 567–74. http://dx.doi.org/10.1115/1.1638784.

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In 1982, the American Society for Testing and Materials (ASTM) adopted consensus standards for direct-normal and hemispherical (“global”) tilted solar terrestrial spectra (ASTM E891/E892/G159). These standard spectra were intended to evaluate photovoltaic (PV) device performance and other solar-related applications. The International Standards Organization (ISO) and International Electrotechnical Commission (IEC) adopted these spectra as spectral standards ISO 9845-1 and IEC 60904-3. Additional information and more accurately representative spectra are needed by today’s PV community. Modern terrestrial spectral radiation models, knowledge of atmospheric physics, and measured radiometric quantities are applied to develop new reference spectra under consideration by ASTM.

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Vagnozzi, Sunny. "New Solar Metallicity Measurements." Atoms 7, no. 2 (April 4, 2019): 41. http://dx.doi.org/10.3390/atoms7020041.

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In the past years, a systematic downward revision of the metallicity of the Sun has led to the “solar modeling problem”, namely the disagreement between predictions of standard solar models and inferences from helioseismology. Recent solar wind measurements of the metallicity of the Sun, however, provide once more an indication of a high-metallicity Sun. Because of the effects of possible residual fractionation, the derived value of the metallicity Z ⊙ = 0 . 0196 ± 0 . 0014 actually represents a lower limit to the true metallicity of the Sun. However, when compared with helioseismological measurements, solar models computed using these new abundances fail to restore agreement, owing to the implausibly high abundance of refractory (Mg, Si, S, Fe) elements, which correlates with a higher core temperature and hence an overproduction of solar neutrinos. Moreover, the robustness of these measurements is challenged by possible first ionization potential fractionation processes. I will discuss these solar wind measurements, which leave the “solar modeling problem” unsolved.

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Zanzi, Andrea, and Barbara Ricci. "Chameleon fields and solar physics." Modern Physics Letters A 30, no. 10 (March 25, 2015): 1550053. http://dx.doi.org/10.1142/s0217732315500534.

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In this paper, we discuss some aspects of solar physics from the standpoint of the so-called chameleon fields (i.e. quantum fields, typically scalar, where the mass is an increasing function of the matter density of the environment). Firstly, we analyze the effects of a chameleon-induced deviation from standard gravity just below the surface of the Sun. In particular, we develop solar models which take into account the presence of the chameleon and we show that they are inconsistent with the helioseismic data. This inconsistency presents itself not only with the typical chameleon setup discussed in the literature (where the mass scale of the potential is fine-tuned to the meV), but also if we remove the fine-tuning on the scale of the potential. However, if we modify standard gravity only in a shell of thickness 10-6 R⊙ just below the solar surface, the model is basically indistinguishable from a Standard Solar Model. Secondly, we point out that, in a model recently considered in the literature (we call this model "Modified Fujii's Model"), a conceivable interpretation of the solar oscillations is given by quantum vacuum fluctuations of a chameleon.

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Christensen-Dalsgaard, Jørgen. "Interior Structure of the Sun." Symposium - International Astronomical Union 142 (1990): 23–34. http://dx.doi.org/10.1017/s0074180900087659.

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Observations of solar oscillations have provided us with detailed information about the solar interior. Here I consider three examples of results obtained in such helioseismic investigations: i) the effect of the equation of state on the comparison between observed and theoretical frequencies; ii) a determination of the depth of the solar convection zone; and iii) indications of deviations from standard models of the structure of the solar core.

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Guzik, Joyce A., C. J. Fontes, P. Walczak, S. R. Wood, K. Mussack, and E. Farag. "Sound speed and oscillation frequencies for solar models evolved with Los Alamos ATOMIC opacities." Proceedings of the International Astronomical Union 11, A29B (August 2015): 532–35. http://dx.doi.org/10.1017/s1743921316006062.

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AbstractLos Alamos National Laboratory has calculated a new generation of radiative opacities (OPLIB data using the ATOMIC code) for elements with atomic number Z = 1-30 with improved physics input, updated atomic data, and finer temperature grid to replace the Los Alamos LEDCOP opacities released in the year 2000. We calculate the evolution of standard solar models including these new opacities, and compare with models evolved using the Lawrence Livermore National Laboratory OPAL opacities (Iglesias & Rogers 1996). We use the solar abundance mixture of Asplund et al. 2009. The Los Alamos ATOMIC opacities (Colgan et al. 2013a, 2013b, 2015) have steeper opacity derivatives than those of OPAL for temperatures and densities of the solar interior radiative zone. We compare the calculated nonadiabatic solar oscillation frequencies and solar interior sound speed to observed frequencies and helioseismic inferences. The calculated sound-speed profiles are similar for models evolved using either the updated Iben evolution code (see Guzik & Mussack 2010), or the MESA evolution code (Paxton et al. 2015). The LANL ATOMIC opacities partially mitigate the ‘solar abundance problem’.

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Nissen, K. M., K. Matthes, U. Langematz, and B. Mayer. "Towards a better representation of the solar cycle in general circulation models." Atmospheric Chemistry and Physics 7, no. 20 (October 17, 2007): 5391–400. http://dx.doi.org/10.5194/acp-7-5391-2007.

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Abstract. We introduce the improved Freie Universität Berlin (FUB) high-resolution radiation scheme FUBRad and compare it to the 4-band standard ECHAM5 SW radiation scheme of Fouquart and Bonnel (FB). Both schemes are validated against the detailed radiative transfer model libRadtran. FUBRad produces realistic heating rate variations during the solar cycle. The SW heating rate response with the FB scheme is about 20 times smaller than with FUBRad and cannot produce the observed temperature signal. A reduction of the spectral resolution to 6 bands for solar irradiance and ozone absorption cross sections leads to a degradation (reduction) of the solar SW heating rate signal by about 20%. The simulated temperature response agrees qualitatively well with observations in the summer upper stratosphere and mesosphere where irradiance variations dominate the signal. Comparison of the total short-wave heating rates under solar minimum conditions shows good agreement between FUBRad, FB and libRadtran up to the middle mesosphere (60–70 km) indicating that both parameterizations are well suited for climate integrations that do not take solar variability into account. The FUBRad scheme has been implemented as a sub-submodel of the Modular Earth Submodel System (MESSy).

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Sonoi, T., R. Samadi, K. Belkacem, H. G. Ludwig, E. Caffau, and B. Mosser. "Analysis of surface effect on solar-like oscillation frequencies using 3D hydrodynamical models." EAS Publications Series 82 (2019): 253–58. http://dx.doi.org/10.1051/eas/1982025.

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We evaluate the frequency difference between standard stellar models and models patched with 3D hydrodynamical models across the Teff–g plane. It allows us to constrain frequency corrections for surface effect. The coefficients in the correction functionals are thus provided as functions of effective temperature and surface gravity.

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Anderson, E., H. M. Antia, S. Basu, B. Chaboyer, S. M. Chitre, J. Christensen-Dalsgaard, A. Eff-Darwich, et al. "The seismic structure of the Sun from GONG." Symposium - International Astronomical Union 181 (1997): 151–58. http://dx.doi.org/10.1017/s0074180900061106.

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This paper is an interim report of our inferences about the hydrostatic structure of the Sun, following the first report of the GONG team in Science (Gough et al., 1996). That work confirms that the spherically averaged structure of the Sun is more or less in agreement with current standard solar models. However, there remain some significant deviations which we regard as important clues to the existence of dynamical phenomena which are not taken into account in standard solar modelling.

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Wang, Ji-Yao, Chao-Jun Feng, Xiang-Hua Zhai, and Xin-Zhou Li. "Solar system tests of a new class of f(z) theory." International Journal of Modern Physics D 29, no. 08 (June 2020): 2050060. http://dx.doi.org/10.1142/s0218271820500601.

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Recently, a new kind of [Formula: see text] theory is proposed to provide a different perspective for the development of reliable alternative models of gravity in which the [Formula: see text] Lagrangian terms are reformulated as polynomial parametrizations [Formula: see text]. In the previous study, the parameters in the [Formula: see text] models have been constrained by using cosmological data. In this paper, these models will be tested by the observations in the solar system. After solving the Ricci scalar as a function of the redshift, one could obtain [Formula: see text] that could be used to calculate the standard Parametrized-Post-Newtonian (PPN) parameters. First, we fit the parametric models with the latest cosmological observational data. Then, the tests are performed by solar system observations. And last we combine the constraints of solar system and cosmology together and reconstruct the [Formula: see text] actions of the [Formula: see text] parametric models.

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Olatona, Gbadebo I. "Estimating Global Solar Radiation from Routine Meteorological Parameters Over a Tropical City (7.23°N; 3.52°E) Using Quadratic Models." Annals of West University of Timisoara - Physics 60, no. 1 (August 1, 2018): 45–55. http://dx.doi.org/10.2478/awutp-2018-0005.

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AbstractThe need for adequate solar radiation is ever increasing for various applications. However there is an inadequate data of solar radiation in many countries due to the cost of instrument set up. Hence this study investigates two models for estimating solar radiation from routinely measured meteorological parameters. The data were obtained from the International Institute of Tropical Agriculture, Ibadan. The regression coefficients of the quadratic models were determined and used to estimate the global solar radiation for both forward and backward predictions. Their predictive accuracies were compared with four other models and the measured values using standard statistical error indicators. The results showed for forward as compared to backward predictions in bracket root mean square errors 1.2 (1.1); mean bias errors 1.1 (0.8) and mean percentage errors -4.8% (-2.9%) while for backward prediction 1.9 (1.7), 1.7 (1.4) and 7.9% (2.2%) measured in KJm−2day−1 respectively. A positive error value shows an over estimation while a negative value shows an under estimation. The models are versatile for estimating global solar radiation at the horizontal surface, fixing missing data and correcting outliers.

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Spergel, David N. "Solar Cosmions." International Astronomical Union Colloquium 121 (1990): 145–52. http://dx.doi.org/10.1017/s0252921100067890.

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AbstractTwo of the outstanding problems in astrophysics are the solar neutrino problem and the missing mass problem. The “solar cosmion”, a weakly interacting massive particle, could solve both problems. Several particle physics models have been suggested for the solar cosmion.The solar cosmion may have other interesting astrophysical effects. It will alter the predicted helioseismology spectrum, effect horizontal branch evolution and may alter the mass-radius relationship in low mass stars. These considerations constrain solar cosmion properties.Several laboratories have begun an active experimental search for the solar cosmion. The UCSB-UCB-Saclay silicon experiment in the Oroville mine has already placed stringent limits on solar cosmions that couple to matter through spin-independent interactions. A planned Saclay experiment may either detect or rule out the existence of “solar cosmions”.The Sun is an powerful laboratory for exploring particle physics beyond the standard model. Even if “solar cosmions” do not exist, the Sun can help “illuminate” the search for other weakly interacting particles posited as solutions to the missing mass problem.

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Brun, A. S., S. Turck‐Chieze, and J. P. Zahn. "Standard Solar Models in the Light of New Helioseismic Constraints. II. Mixing below the Convective Zone." Astrophysical Journal 525, no. 2 (November 10, 1999): 1032–41. http://dx.doi.org/10.1086/307932.

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Goode, P. "Seismic Solar Model." Highlights of Astronomy 10 (1995): 326–27. http://dx.doi.org/10.1017/s1539299600011370.

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The method of frequency inversion reveals that within the quoted observational errors, it is possible to achieve a precision of ∼ 10−3 in the sound speed determination through most of the Sun’s interior. Only for r < 0.05R⊙ is the precision ∼ 10−2. The accuracy of the density and pressure determinations is only slightly worse. Such restrictions impose significant constraints on the microscopic physical data, i.e. opacities, nuclear reaction cross-sections, and diffusion coefficients as well as on the solar age. The helioseismic age is consistent with that from meteorites.Recently released low-l solar oscillation data from the BISON network combined with BBSO data yield the most up-to-date solar seismic model of the Sun’s interior. For the core, the solar seismic model from the new data are consistent with the best, current standard solar models. An astrophysical solution to the solar neutrino problem fades away.

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Felipe, T., and C. R. Sangeetha. "Numerical determination of the cutoff frequency in solar models." Astronomy & Astrophysics 640 (July 28, 2020): A4. http://dx.doi.org/10.1051/0004-6361/202038387.

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Context. In stratified atmospheres, acoustic waves can only propagate if their frequency is higher than the cutoff value. The determination of the cutoff frequency is fundamental for several topics in solar physics, such as evaluating the contribution of the acoustic waves to the chromospheric heating or the application of seismic techniques. However, different theories provide different cutoff values. Aims. We developed an alternative method to derive the cutoff frequency in several standard solar models, including various quiet-Sun and umbral atmospheres. The effects of magnetic field and radiative losses on the cutoff are examined. Methods. We performed numerical simulations of wave propagation in the solar atmosphere using the code MANCHA. The cutoff frequency is determined from the inspection of phase-difference spectra computed between the velocity signal at two atmospheric heights. The process is performed by choosing pairs of heights across all the layers between the photosphere and the chromosphere to derive the vertical stratification of the cutoff in the solar models. Result. The cutoff frequency predicted by the theoretical calculations departs significantly from the measurements obtained from the numerical simulations. In quiet-Sun atmospheres, the cutoff shows a strong dependence on the magnetic field for adiabatic wave propagation. When radiative losses are taken into account, the cutoff frequency is greatly reduced and the variation of the cutoff with the strength of the magnetic field is lower. The effect of the radiative losses in the cutoff is necessary to understand recent quiet-Sun and sunspot observations. In the presence of inclined magnetic fields, our numerical calculations confirm that the cutoff frequency is reduced as a result of the reduced gravity experienced by waves that propagate along field lines. An additional reduction is also found in regions with significant changes in the temperature, which is due to the lower temperature gradient along the path of field-guided waves. Conclusions. Our results show solid evidence that the cutoff frequency in the solar atmosphere is stratified. The cutoff values are not correctly captured by theoretical estimates. In addition, most of the widely used analytical cutoff formulae neglect the effect of magnetic fields and radiative losses, whose role is critical for determining the evanescent or propagating nature of the waves.

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Machlev, Ram, Zohar Batushansky, Sachin Soni, Vladimir Chadliev, Juri Belikov, and Yoash Levron. "Verification of Utility-Scale Solar Photovoltaic Plant Models for Dynamic Studies of Transmission Networks." Energies 13, no. 12 (June 19, 2020): 3191. http://dx.doi.org/10.3390/en13123191.

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In recent years, there has been a growing need for accurate models that describe the dynamics of renewable energy sources, especially photovoltaic sources and wind turbines. In light of this gap, this work focuses on the validation of standard dynamic models developed by the Western Electricity Coordinating Council (WECC), using actual measurements from the Western Texas and Southern California transmission networks. The tests are based on the North American Electric Reliability Corporation compliance standards and include dynamic stability tests for volt-varcontrol and primary frequency response. Through an extensive set of field tests, we show that the WECC generic models can be used to simulate real dynamic phenomena in large-scale solar photovoltaic power plants, and we propose guidelines for correct usage of these models. The results show that the WECC models are especially accurate when the photovoltaic system is connected with a low impedance to the main network. We also show that the tested WECC models successfully predict the frequency response of an actual grid event that occurred in the Electric Reliability Council of Texas and which resulted in a loss of nearly 1.365 GW. This result supports the use of these models in the study of large-scale dynamic phenomena that include renewable energy sources.

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Supriya, H. D., H. N. Smitha, K. N. Nagendra, J. O. Stenflo, M. Bianda, B. Ravindra, R. Ramelli, and L. S. Anusha. "Modeling the center-to-limb variation of the Ca i 4227 Å line using FCHHT models." Proceedings of the International Astronomical Union 10, S305 (December 2014): 381–86. http://dx.doi.org/10.1017/s1743921315005098.

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AbstractThe Ca i 4227 Å is a chromospheric line exhibiting the largest degree of linear polarization near the limb, in the visible spectrum of the Sun. Modeling the observations of the center-to-limb variations (CLV) of different lines in the Second Solar Spectrum helps to sample the height dependence of the magnetic field, as the observations made at different lines of sight sample different heights in the solar atmosphere. Supriya et al. (2014) attempted to simultaneously model the CLV of the (I, Q/I) spectra of the Ca i 4227 Å line using the standard 1-D FAL model atmospheres. They found that the standard FAL model atmospheres and also any appropriate combination of them, fail to simultaneously fit the observed Stokes (I, Q/I) profiles at all the limb distances (μ) satisfying at the same time all the observational constraints. This failure of 1-D modeling approach can probably be overcome by using multi-dimensional modeling which is computationally expensive. To eliminate an even wider choice of 1-D models, we attempt here to simultaneously model the CLV of the (I, Q/I) spectra using the FCHHT solar model atmospheres which are updated and recent versions of the FAL models. The details of our modeling efforts and the results are presented.

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García-Rodríguez, Ana, Sol García-Rodríguez, Montserrat Díez-Mediavilla, and Cristina Alonso-Tristán. "Photosynthetic Active Radiation, Solar Irradiance and the CIE Standard Sky Classification." Applied Sciences 10, no. 22 (November 12, 2020): 8007. http://dx.doi.org/10.3390/app10228007.

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Plant growth is directly related to levels of photosynthetic photon flux density, Qp. The improvement of plant-growth models therefore requires accurate estimations of the Qp parameter that is often indirectly calculated on the basis of its relationship with solar irradiation, RS, due to the scarcity of ground measurements of photosynthetic photon flux density. In this experimental campaign in Burgos, Spain, between April 2019 and January 2020, an average value of the Qp/Rs ratio is determined on the basis of measurements at ten-minute intervals. The most influential factor in the Qp/Rs ratio, over and above any daily or seasonal pattern, is the existence of overcast sky conditions. The CIE standard sky classification can be used to establish an unequivocal characterization of the cloudiness conditions of homogeneous skies. In this study, the relation between the CIE standard sky type and Qp/Rs is investigated. Its conclusions were that the Qp/Rs values, the average of which was 1.93±0.15 μmol·J−1, presented statistically significant differences for each CIE standard sky type. The overcast sky types presented the highest values of the ratio, while the clear sky categories presented the lowest and most dispersed values. During the experimental campaign, only two exceptions were noted for covered and partial covered sky-type categories, respectively, sky types 5 and 9. Their values were closer to those of categories classified as clear sky according to the CIE standard. Both categories presented high uniformity in terms of illumination.

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Journal articles on the topic 'Standard solar models'

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